Vehicle vision system with lens pollution detection

ABSTRACT

A vision system for a vehicle includes a camera having an imaging array having multiple columns of photosensing elements and multiple rows of photosensing elements, with the columns of photosensing elements being generally vertically orientated and the rows of photosensing elements being generally horizontally orientated relative to ground. The multiple rows of photosensing elements comprising top rows, middle rows and bottom rows. When the vehicle is moving, top row brightness values at top rows, middle row brightness values at middle rows, and bottom row brightness values at bottom rows are determined by processing of captured image data by a processor. Contrast of middle row brightness values compared to bottom row brightness values or top row brightness values is determined and, based on determined contrast of middle row brightness values compared to bottom row brightness values or top row brightness values, an at least partial blockage of the camera is detected.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/851,378, filed Mar. 27, 2013, now U.S. Pat. No. 9,319,637,which claims the filing benefit of U.S. provisional application, Ser.No. 61/616,126, filed Mar. 27, 2012, which is hereby incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to imaging systems or vision systems forvehicles.

BACKGROUND OF THE INVENTION

Use of imaging sensors in vehicle imaging systems is common and known.Examples of such known systems are described in U.S. Pat. Nos.5,949,331; 5,670,935 and/or 5,550,677, which are hereby incorporatedherein by reference in their entireties.

SUMMARY OF THE INVENTION

The present invention provides a vision system or imaging system for avehicle that utilizes one or more cameras to capture images exterior ofthe vehicle, and provides the communication/data signals, includingcamera data or image data, that may be displayed at a display screenthat is viewable by the driver of the vehicle, such as when the driveris backing up the vehicle, and that may be processed and, responsive tosuch image processing, the system may detect an object at or near thevehicle and in the path of travel of the vehicle, such as when thevehicle is backing up. The vision system is operable detect pollution orcontaminants, such as water, mud, salt and/or the like, that is/aredisposed at the lens or cover of the camera, and may generate an alertor may operate to clean or wipe the lens or cover in response todetection of a threshold degree of pollution or contaminants at or onthe lens or cover.

According to an aspect of the present invention, a vision system for avehicle includes at least one camera or image sensor disposed at avehicle and having a field of view exterior of the vehicle, and aprocessor operable to process data transmitted by the camera. The visionsystem may be operable to compare contrast ratios of outputs ofphotosensing elements or pixels of the pixelated imaging array of thecamera or imager to determine if some of the pixels are blocked bycontaminants or the like at the lens of the camera, and/or the visionsystem may be operable to monitor pixels of the pixelated imaging arrayand, when the pixels fit a Gaussian distribution, the processor orsystem may classify the pixels as blocked pixels and, responsive to adetermination that a number of blocked pixels is greater than athreshold level, the processor determines that there are contaminants atthe lens of the camera. Responsive to the processor determining thatthere are contaminants at the lens of the camera, the system maygenerate an alert and/or adapt processing of image data to at leastpartially accommodate for the presence of the determined contaminantsand/or clean the lens. The processor or algorithm may be incorporated incircuitry of the camera, or the processor or algorithm may beincorporated in circuitry of a control of the vehicle or a control ofthe vision system that is separate from the camera and camera circuitry.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a vehicle with a vision system and imagingsensors or cameras that provide exterior fields of view in accordancewith the present invention;

FIG. 2 is a table of auto exposure (AE) zone labels for an exemplaryimager for a vehicle vision system;

FIG. 3 is a table of AE zone brightness registers for an exemplaryimager;

FIG. 4 is a flow chart of a pollution detection algorithm of the presentinvention;

FIG. 5 is an image captured by an imager showing an exemplary scene asprocessed by a pollution detection algorithm of the present invention;and

FIG. 6 is a flow chart of an ECU-based algorithm of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle vision system and/or driver assist system and/or objectdetection system and/or alert system operates to capture images exteriorof the vehicle and may process the captured image data to display imagesand to detect objects at or near the vehicle and in the predicted pathof the vehicle, such as to assist a driver of the vehicle in maneuveringthe vehicle in a rearward direction. The vision system includes aprocessor that is operable to receive image data from one or morecameras and may provide a displayed image that is representative of thesubject vehicle (such as for a top down or bird's eye or surround view,such as discussed below).

Referring now to the drawings and the illustrative embodiments depictedtherein, a vehicle 10 includes an imaging system or vision system 12that includes at least one exterior facing imaging sensor or camera,such as a rearward facing imaging sensor or camera 14 a (and the systemmay optionally include multiple exterior facing imaging sensors orcameras, such as a forwardly facing camera 14 b at the front (or at thewindshield) of the vehicle, and a sidewardly/rearwardly facing camera 14c, 14 b at respective sides of the vehicle), which captures imagesexterior of the vehicle, with the camera having a lens for focusingimages at or onto an imaging array or imaging plane or imager of thecamera (FIG. 1). The vision system 12 includes a control or processor 18that is operable to process image data captured by the cameras and mayprovide displayed images at a display device 16 for viewing by thedriver of the vehicle (although shown in FIG. 1 as being part of orincorporated in or at an interior rearview mirror assembly 20 of thevehicle, the control and/or the display device may be disposed elsewhereat or in the vehicle).

The present invention provides algorithms that are used in visionsystems and/or automotive cameras to identify and detect the degree thata lens on a camera is polluted by water droplets, mud or salt, so as todetermine when the pollution is to a degree that the camera'sperformance may be substantially or severely reduced, and in automotivecamera applications, when the driver's ability to use or view thecamera's video is impaired or when the machine vision processor'sperformance is substantially or significantly impaired. It is desiredthat, in any of the described scenarios, the algorithms will determinethe degree of pollution and give out warning signals, messages ordirectly control certain mechanisms to clean the lens of the camera. Thepresent invention provides two pollution detection algorithms, where thefirst algorithm (which uses or requires a reduced amount of processingpower) may be implemented directly in a camera and the second algorithm(which uses or requires more processing power) may be implemented in acontrol or electronic control unit (ECU) of the vehicle or a control ofthe vision system that may be separate and remote from the camera and/orcamera circuitry.

Due to the minimum processing power and data bandwidth of an automotiverear view camera, it is not readily feasible to use image processingsoftware on the microprocessor to identify the pollution, because suchprocessing usually demands a high amount of processing power. Thepresent invention thus provides a method for detecting pollution byreading a limited number of imager register values. The algorithmdetects pollution by checking the contrast of auto exposure (AE) controlzones when an AE function or feature is enabled and the camera's hostvehicle is traveling in a forward or rearward direction or drivingcondition. Normally, in a typical camera imager (such as a twodimensional array of photosensing elements or pixels) used in automotivecamera applications, the sensing area of the imager is divided intomultiple zones (such as, for example, 5×5 zones or other sized zones)that allows each zone's pixels to be averaged in brightness and colorvalues. The camera's or imager's auto exposure and auto white balancecan be controlled by reading the zone brightness and color values of allzones. This first algorithm is based on the arithmetic calculations ofthe brightness values of all zones.

Tests on different roads at different times show that the contrast of AEzones has a large range (0-1) for a clean lens with little or nopollution and a small range (0-0.3) for a moderately polluted lens. Toreliably detect the pollution on the lens, multiple AE zone contrasts(such as 10 used for the illustrated embodiment) are checked. Those AEzone contrasts includes the contrasts of the following AE zone pairs,1-11, 2-12, 3-13, 4-14, 5-15, 6-16, 7-17, 8-18, 9-19, 10-20. The AE zonelabels are shown in FIG. 2. As an example, in an Aptina CMOS imagerMT9V128 (which is a CMOS imager with VGA resolution), the registers forcorresponding AE zone brightness are listed in FIG. 3.

The basic concept of the first algorithm is as follows. In a typicalautomotive rear view camera, the scene imaged by the imager typicallyhas the sky (above the horizon) imaged in the first or upper rows andthe vehicle bumper in the last or lower row or rows, counting from topto bottom of the captured image. The middle rows of zones mostly imageor show the road, ground, buildings, parked or passing vehicles andother objects. When the camera's host vehicle drives forward (orrearward) on the road, the zones in the middle rows will experience morechanges of averaged brightness values of the zones than the ones in thetop and bottom rows. By calculating the difference or contrast of thebrightness values between the middle zones and zones in the top orbottom rows, either in the same column or the different column, thesystem can determine if a normal view is blocked or partially blocked,or polluted, by the substances (such as dirt, debris, moisture or thelike) on the lens. In the case of a lens that is partially blocked, thecontrast will be lower than the contrast of the same or similar zoneswith a clean lens. This is because when a part of camera lens is blockedby some substances (such as, for example, water droplets, salt, mudand/or the like), some light rays are blocked and cannot reach theimager as they normally do. As a result, some areas of the imager appeardarker or have lower brightness values, and the contrast of the scene inthese areas become lower.

Furthermore, when the vehicle moves along the road, the moving sceneimaged by the imager generates less pixel value fluctuation or variationwhen the lens is polluted. The amount of reduced pixel value fluctuationgrows with the amount of pollution on lens. In principle, one cancompute the above values at every pixel of the imager, but doing sorequires a significant amount of processing power and data transferbandwidth. Instead, the system or process of the present invention usesthe imager's existing average pixel brightness values of AE zones tocompute the pollution level at the lens. This requires a reduced orminimum amount of computing power and data traffic. A microprocessorwith limited processing power and with an I2C or SPI communicationchannel with the imager, which is typical for a rear view camera of avehicle, is adequate for running the algorithm. The algorithm can alsobe built into the imager's system-on-chip (SOC) part to perform theabove algorithm without using an external microprocessor.

Furthermore, the same algorithm can also be implemented in a separateprocessor that can calculate pollution level based only on the videoinput from a separate camera. In such a configuration or implementation,the computation can be based on pixel brightness or zone brightnessaverage.

A flow chart of the pollution detection algorithm or process 110 isshown in FIG. 4. The process 110 starts at 102, and initializes acontrast maximum or max value and a contrast minimum or min value at104. The process reads the registers for AE zone brightness for oneframe at 106 (such as by reading AE zones 1-20), and calculates thecurrent contrasts of interested AE zones at 108. If the systemdetermines at 110 that the calculated contrast is greater than thecontrast max value, then the contrast max value is set to the currentcontrast value at 112 and then the process continues to 114. However, ifthe system determines at 110 that the calculated contrast is not greaterthan the contrast max, then the process continues to 114. If the systemdetermines at 114 that the calculated contrast is less than the contrastmin value, then the contrast min value is set to the current contrastvalue at 116 and then the process continues to 118. However, if thesystem determines at 114 that the calculated contrast is not less thanthe contrast min value, then the process continues to 118. If the systemhas not completed the N iterations at 118, then the system returns to106 and continues. If the system has completed the N iterations at 118,then the contrast range is set to be the difference between the contrastmax and contrast min values at 120. If the system determines at 122 thatthe contrast range is less than a contrast threshold, then the systemdetermines that there is pollution present at the lens (such as athreshold degree of pollution), and the system may generate an alert orreport to report the pollution at 124 (such as providing a visual oraudible report or alert to the driver of the vehicle). If the systemdetermines at 122 that the contrast range is not less than a contrastthreshold, then the system determines that there is no pollution (orthere is less than a threshold amount of pollution) present at the lensand returns to 104 and repeats the process. Optionally, the system,responsive to a determination of pollution at the lens, may generate analert or report and/or adapt the processing of image data to at leastpartially accommodate for the presence of the determined contaminants atthe camera lens and/or clean the lens (such as via a fluid spray orwiping system or the like).

The second algorithm of the present invention preferably is implementedto run in a vehicle controller or control unit or ECU. Each pixel in theimage is modeled as several Gaussians distributions. The system requiresan initial training period (such as, for example, about 30 frames, orapproximately 1 second of video) along with the scene changing (movementof the vehicle) in order to operate. If the vehicle remains stationaryand the algorithm continued to run, all pixels would be flagged as notchanging.

At each frame, the algorithm computes whether the pixel value remainedstatic (the pixel value fit one of the Gaussian distributions) or thepixel value changed (the pixel value did not fit one of the Gaussiandistributions). The Gaussian mixture model was chosen because it isrobust to various lighting conditions, which leads to fewer numbers offalse positives. When the number of pixels that have been classified as“not changing” exceeds a threshold (such as, for example, about 30percent of the image or any suitable or selected percentage of theimage), a blockage condition is identified. FIG. 5 depicts an examplescene with this algorithm running, where the solid pixels or pixel areas30 are representative of pixels that have not had any change.

FIG. 6 shows the flow chart of the second algorithm or ECU-basedalgorithm. The second algorithm or process 130 starts at 132 and, if thesystem determines at 134 that the vehicle is moving faster than athreshold level, then the system determines, at 136, whether or not thealgorithm has been trained. If the system determines that the vehicle isnot moving, then the process does not continue. If the vehicle ismoving, but the algorithm has not been trained, then the systeminitializes the Gaussian distributions with the first 30 frames (orother suitable number of frames) of video images at 138 and thencontinues to 140, where the algorithm loops over each pixel in the newimage. At 142, the system determines if the pixel fits one of theGaussian distributions, and if so, it classifies the pixel as notchanged or blocked at 144, and if not, the system classifies the pixelas changed at 146. The process then continues at 148, where the systemdetermines whether or not the ratio of pixels classified as blocked isgreater than a threshold level. If the ratio is greater than thethreshold level, the system reports a blockage condition at 160. If theratio is not greater than the threshold level, the system returns to 134and continues.

Therefore, the present invention provides a vision system for a vehiclethat includes a processor or head unit and a camera or cameras mountedat the vehicle. The system or process is operable to determine if thereis pollution or dirt or contaminants present at a lens or cover of anexterior camera of a vehicle vision system (or an interiorly disposedcamera that views through a cover or lens that may be exposed at theexterior of the vehicle). The system or process or algorithm may beincorporated in the circuitry of the camera or may be incorporated in avehicle-based control or control of the vehicle or vision system.Optionally, a system or algorithm of the present invention (that may beoperated or processed by the circuitry of the imager or camera) may beoperable to read a limited number of imager register values, and maydetect pollution by checking the contrast of auto exposure (AE) controlzones when an AE function or feature is enabled and the camera's hostvehicle is traveling in a forward (or rearward) direction or drivingcondition. When the range of contrast levels of the pixels are less thana threshold level, such that the contrast levels are not changing athreshold amount as the vehicle is moved, then the system or process oralgorithm may determine that there is pollution or contaminants at thelens or cover of the imager.

Optionally, a system or algorithm of the present invention (that may beincorporated in or operated by a control of the vehicle or of thevehicle vision system and separate from the circuitry of the imager orcamera) may be operable to process or monitor each pixel (or asubstantial number of pixels) of an imager and if the pixel(s) fits aGaussian distribution (that is based on a number of frames of the videoimages), the process or algorithm may classify the pixel as not changedor blocked, and then the system determines whether or not the ratio ofpixels classified as blocked is greater than a threshold level, and ifso, the system may determine a blockage condition.

Based on a result or output of either algorithm, the system may generatean alert to the driver of a blockage condition, or may clean the coveror lens (such as by utilizing aspects of the vision systems and camerasdescribed in U.S. Pat. No. 7,965,336, which is hereby incorporatedherein by reference in its entirety). Optionally, the system may,responsive to detection of or a determination of the presence of dirt orcontaminants at the lens, adjust the processing of image data capturedby that camera to accommodate or account for the determined dirt orcontaminants that are present at the lens. Optionally, the system mayutilize aspects of the dirt detection and camera protection systemsdescribed in U.S. provisional application Ser. No. 61/713,772, filedOct. 15, 2012; Ser. No. 61/766,883, filed Feb. 20, 2013; and/or Ser. No.61/804,786, filed Mar. 25, 2013, which are hereby incorporated herein byreference in their entireties.

The system includes an image processor operable to process image datacaptured by the camera or cameras, such as for detecting objects orother vehicles or pedestrians or the like in the field of view of one ormore of the cameras. For example, the image processor may comprise anEyeQ2 or EyeQ3 image processing chip available from Mobileye VisionTechnologies Ltd. of Jerusalem, Israel, and may include object detectionsoftware (such as the types described in U.S. Pat. Nos. 7,855,755;7,720,580 and/or 7,038,577, which are hereby incorporated herein byreference in their entireties), and may analyze image data to detectvehicles and/or other objects. Responsive to such image processing, andwhen an object or other vehicle is detected, the system may generate analert to the driver of the vehicle and/or may generate an overlay at thedisplayed image to highlight or enhance display of the detected objector vehicle, in order to enhance the driver's awareness of the detectedobject or vehicle or hazardous condition during a driving maneuver ofthe equipped vehicle.

The vehicle may include any type of sensor or sensors, such as imagingsensors or radar sensors or lidar sensors or ladar sensors or ultrasonicsensors or the like. The imaging sensor or camera may capture image datafor image processing and may comprise any suitable camera or sensingdevice, such as, for example, an array of a plurality of photosensorelements arranged in at least 640 columns and 480 rows (at least a640×480 imaging array and optionally a mega-pixel array that provideshigh definition imaging), with a respective lens focusing images ontorespective portions of the array. The photosensor array may comprise aplurality of photosensor elements arranged in a photosensor array havingrows and columns. The logic and control circuit of the imaging sensormay function in any known manner, and the image processing andalgorithmic processing may comprise any suitable means for processingthe images and/or image data. For example, the vision system and/orprocessing and/or camera and/or circuitry may utilize aspects describedin U.S. Pat. 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No. 13/848,796, filed Mar. 22, 2013 andpublished Oct. 24, 2013 as U.S. Publication No. US-2013-0278769; Ser.No. 13/847,815, filed Mar. 20, 2013 and published Oct. 31, 2013 as U.S.Publication No. US-2013-0286193; Ser. No. 13/779,881, filed Feb. 28,2013 and published Sep. 5, 2013 as U.S. Publication No. US-2013-0231825;Ser. No. 13/785,099, filed Mar. 5, 2013 and published Sep. 19, 2013 asU.S. Publication No. US-2013-0242099; Ser. No. 13/774,317, filed Feb.22, 2013, now U.S. Pat. No. 9,269,263; Ser. No. 13/774,315, filed Feb.22, 2013 and published Aug. 22, 2013 as U.S. Publication No.US-2013-0215271; Ser. No. 13/681,963, filed Nov. 20, 2012, now U.S. Pat.No. 9,264,673; Ser. No. 13/660,306, filed Oct. 25, 2012, now U.S. Pat.No. 9,146,898; Ser. No. 13/653,577, filed Oct. 17, 2012, now U.S. Pat.No. 9,174,574; and/or Ser. No. 13/534,657, filed Jun. 27, 2012 andpublished Jan. 3, 2013 as U.S. Publication No. US-2013-0002873, and/orU.S. provisional application Ser. No. 61/733,598, filed Dec. 5, 2012;Ser. No. 61/733,093, filed Dec. 4, 2012; Ser. No. 61/710,924, filed Oct.8, 2012; Ser. No. 61/696,416, filed Sep. 4, 2012; Ser. No. 61/682,995,filed Aug. 14, 2012; Ser. No. 61/682,486, filed Aug. 13, 2012; Ser. No.61/680,883, filed Aug. 8, 2012; Ser. No. 61/678,375, filed Aug. 1, 2012;Ser. No. 61/676,405, filed Jul. 27, 2012; Ser. No. 61/666,146, filedJun. 29, 2012; Ser. No. 61/653,665, filed May 31, 2012; Ser. No.61/653,664, filed May 31, 2012; Ser. No. 61/648,744, filed May 18, 2012;and/or Ser. No. 61/624,507, filed Apr. 16, 2012, which are all herebyincorporated herein by reference in their entireties. The system maycommunicate with other communication systems via any suitable means,such as by utilizing aspects of the systems described in PCT ApplicationNo. PCT/US10/038477, filed Jun. 14, 2010, and/or U.S. patent applicationSer. No. 13/202,005, filed Aug. 17, 2011, now U.S. Pat. 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The imaging device and control and image processor and any associatedillumination source, if applicable, may comprise any suitablecomponents, and may utilize aspects of the cameras and vision systemsdescribed in U.S. Pat. Nos. 5,550,677; 5,877,897; 6,498,620; 5,670,935;5,796,094; 6,396,397; 6,806,452; 6,690,268; 7,005,974; 7,123,168;7,004,606; 6,946,978; 7,038,577; 6,353,392; 6,320,176; 6,313,454 and6,824,281, and/or International Publication No. WO 2010/099416,published Sep. 2, 2010, and/or PCT Application No. PCT/US10/47256, filedAug. 31, 2010 and published Mar. 10, 2011 as International PublicationNo. WO 2011/028686, and/or U.S. patent application Ser. No. 12/508,840,filed Jul. 24, 2009, and published Jan. 28, 2010 as U.S. Pat.Publication No. US 2010-0020170, and/or PCT Application No.PCT/US2012/048110, filed Jul. 25, 2012 and published Jan. 31, 2013 asInternational Publication No. WO 2013/016409, and/or U.S. patentapplication Ser. No. 13/534,657, filed Jun. 27, 2012 and published Jan.3, 2013 as U.S. Publication No. US-2013-0002873, which are all herebyincorporated herein by reference in their entireties. The camera orcameras may comprise any suitable cameras or imaging sensors or cameramodules, and may utilize aspects of the cameras or sensors described inU.S. patent application Ser. No. 12/091,359, filed Apr. 24, 2008 andpublished Oct. 1, 2009 as U.S. Publication No. US-2009-0244361, and/orSer. No. 13/260,400, filed Sep. 26, 2011, now U.S. Pat. No. 8,542,451,and/or U.S. Pat. No. 7,965,336 and/or 7,480,149, which are herebyincorporated herein by reference in their entireties. The imaging arraysensor may comprise any suitable sensor, and may utilize various imagingsensors or imaging array sensors or cameras or the like, such as a CMOSimaging array sensor, a CCD sensor or other sensors or the like, such asthe types described in U.S. Pat. Nos. 5,550,677; 5,670,935; 5,760,962;5,715,093; 5,877,897; 6,922,292; 6,757,109; 6,717,610; 6,590,719;6,201,642; 6,498,620; 5,796,094; 6,097,023; 6,320,176; 6,559,435;6,831,261; 6,806,452; 6,396,397; 6,822,563; 6,946,978; 7,339,149;7,038,577; 7,004,606 and/or 7,720,580, and/or U.S. patent applicationSer. No. 10/534,632, filed May 11, 2005, now U.S. Pat. No. 7,965,336;and/or PCT Application No. PCT/US2008/076022, filed Sep. 11, 2008 andpublished Mar. 19, 2009 as International Publication No. WO/2009/036176,and/or PCT Application No. PCT/US2008/078700, filed Oct. 3, 2008 andpublished Apr. 9, 2009 as International Publication No. WO/2009/046268,which are all hereby incorporated herein by reference in theirentireties.

The camera module and circuit chip or board and imaging sensor may beimplemented and operated in connection with various vehicularvision-based systems, and/or may be operable utilizing the principles ofsuch other vehicular systems, such as a vehicle headlamp control system,such as the type disclosed in U.S. Pat. Nos. 5,796,094; 6,097,023;6,320,176; 6,559,435; 6,831,261; 7,004,606; 7,339,149 and/or 7,526,103,which are all hereby incorporated herein by reference in theirentireties, a rain sensor, such as the types disclosed in commonlyassigned U.S. Pat. Nos. 6,353,392; 6,313,454; 6,320,176 and/or7,480,149, which are hereby incorporated herein by reference in theirentireties, a vehicle vision system, such as a forwardly, sidewardly orrearwardly directed vehicle vision system utilizing principles disclosedin U.S. Pat. Nos. 5,550,677; 5,670,935; 5,760,962; 5,877,897; 5,949,331;6,222,447; 6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202;6,201,642; 6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452;6,822,563; 6,891,563; 6,946,978 and/or 7,859,565, which are all herebyincorporated herein by reference in their entireties, a trailer hitchingaid or tow check system, such as the type disclosed in U.S. Pat. No.7,005,974, which is hereby incorporated herein by reference in itsentirety, a reverse or sideward imaging system, such as for a lanechange assistance system or lane departure warning system or for a blindspot or object detection system, such as imaging or detection systems ofthe types disclosed in U.S. Pat. Nos. 7,720,580; 7,038,577; 5,929,786and/or 5,786,772, and/or U.S. patent application Ser. No. 11/239,980,filed Sep. 30, 2005, now U.S. Pat. No. 7,881,496, and/or U.S.provisional application Ser. No. 60/628,709, filed Nov. 17, 2004; Ser.No. 60/614,644, filed Sep. 30, 2004; Ser. No. 60/618,686, filed Oct. 14,2004; Ser. No. 60/638,687, filed Dec. 23, 2004, which are herebyincorporated herein by reference in their entireties, a video device forinternal cabin surveillance and/or video telephone function, such asdisclosed in U.S. Pat. Nos. 5,760,962; 5,877,897; 6,690,268 and/or7,370,983, and/or U.S. patent application Ser. No. 10/538,724, filedJun. 13, 2005 and published Mar. 9, 2006 as U.S. Publication No.US-2006-0050018, which are hereby incorporated herein by reference intheir entireties, a traffic sign recognition system, a system fordetermining a distance to a leading or trailing vehicle or object, suchas a system utilizing the principles disclosed in U.S. Pat. No.6,396,397 and/or 7,123,168, which are hereby incorporated herein byreference in their entireties, and/or the like.

Optionally, the circuit board or chip may include circuitry for theimaging array sensor and or other electronic accessories or features,such as by utilizing compass-on-a-chip or EC driver-on-a-chip technologyand aspects such as described in U.S. Pat. No. 7,255,451 and/or U.S.Pat. No. 7,480,149; and/or U.S. patent application Ser. No. 11/226,628,filed Sep. 14, 2005 and published Mar. 23, 2006 as U.S. Publication No.US-2006-0061008, and/or Ser. No. 12/578,732, filed Oct. 14, 2009 andpublished Apr. 22, 2010 as U.S. Publication No. US-2010-0097469, whichare hereby incorporated herein by reference in their entireties.

Optionally, the vision system may include a display for displayingimages captured by one or more of the imaging sensors for viewing by thedriver of the vehicle while the driver is normally operating thevehicle. Optionally, for example, the vision system may include a videodisplay device disposed at or in the interior rearview mirror assemblyof the vehicle, such as by utilizing aspects of the video mirror displaysystems described in U.S. Pat. No. 6,690,268 and/or U.S. patentapplication Ser. No. 13/333,337, filed Dec. 21, 2011, now U.S. Pat. No.9,264,672, which are hereby incorporated herein by reference in theirentireties. The video mirror display may comprise any suitable devicesand systems and optionally may utilize aspects of the compass displaysystems described in U.S. Pat. Nos. 7,370,983; 7,329,013; 7,308,341;7,289,037; 7,249,860; 7,004,593; 4,546,551; 5,699,044; 4,953,305;5,576,687; 5,632,092; 5,677,851; 5,708,410; 5,737,226; 5,802,727;5,878,370; 6,087,953; 6,173,508; 6,222,460; 6,513,252 and/or 6,642,851,and/or European patent application, published Oct. 11, 2000 underPublication No. EP 0 1043566, and/or U.S. patent application Ser. No.11/226,628, filed Sep. 14, 2005 and published Mar. 23, 2006 as U.S.Publication No. US-2006-0061008, which are all hereby incorporatedherein by reference in their entireties. Optionally, the video mirrordisplay screen or device may be operable to display images captured by arearward viewing camera of the vehicle during a reversing maneuver ofthe vehicle (such as responsive to the vehicle gear actuator beingplaced in a reverse gear position or the like) to assist the driver inbacking up the vehicle, and optionally may be operable to display thecompass heading or directional heading character or icon when thevehicle is not undertaking a reversing maneuver, such as when thevehicle is being driven in a forward direction along a road (such as byutilizing aspects of the display system described in PCT Application No.PCT/US2011/056295, filed Oct. 14, 2011 and published Apr. 19, 2012 asInternational Publication No. WO 2012/051500, which is herebyincorporated herein by reference in its entirety).

Optionally, the vision system (utilizing the forward facing camera and arearward facing camera and other cameras disposed at the vehicle withexterior fields of view) may be part of or may provide a display of atop-down view or birds-eye view system of the vehicle or a surround viewat the vehicle, such as by utilizing aspects of the vision systemsdescribed in PCT Application No. PCT/US10/25545, filed Feb. 26, 2010 andpublished on Sep. 2, 2010 as International Publication No. WO2010/099416, and/or PCT Application No. PCT/US10/47256, filed Aug. 31,2010 and published Mar. 10, 2011 as International Publication No. WO2011/028686, and/or PCT Application No. PCT/US2011/062834, filed Dec. 1,2011 and published Jun. 7, 2012 as International Publication No.WO2012/075250, and/or PCT Application No. PCT/US2012/048993, filed Jul.31, 2012 and published Feb. 7, 2013 as International Publication No. WO2013/019795, and/or PCT Application No. PCT/US11/62755, filed Dec. 1,2011 and published Jun. 7, 2012 as International Publication No. WO2012-075250, and/or PCT Application No. PCT/CA2012/000378, filed Apr.25, 2012 and published Nov. 1, 2012 as International Publication No. WO2012/145822, and/or PCT Application No. PCT/US2012/066571, filed Nov.27, 2012 and published Jun. 6, 2013 as International Publication No. WO2013/081985, and/or PCT Application No. PCT/US2012/068331, filed Dec. 7,2012 and published Jun. 13, 2013 as International Publication No. WO2013/086249, and/or PCT Application No. PCT/US2013/022119, filed Jan.18, 2013 and published Jul. 25, 2013 as International Publication No. WO2013/109869, and/or U.S. patent application Ser. No. 13/333,337, filedDec. 21, 2011, now U.S. Pat. No. 9,264,672, which are herebyincorporated herein by reference in their entireties.

Optionally, a video mirror display may be disposed rearward of andbehind the reflective element assembly and may comprise a display suchas the types disclosed in U.S. Pat. Nos. 5,530,240; 6,329,925;7,855,755; 7,626,749; 7,581,859; 7,446,650; 7,370,983; 7,338,177;7,274,501; 7,255,451; 7,195,381; 7,184,190; 5,668,663; 5,724,187 and/or6,690,268, and/or in U.S. patent application Ser. No. 12/091,525, filedApr. 25, 2008, now U.S. Pat. No. 7,855,755; Ser. No. 11/226,628, filedSep. 14, 2005 and published Mar. 23, 2006 as U.S. Publication No.US-2006-0061008; and/or Ser. No. 10/538,724, filed Jun. 13, 2005 andpublished Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, whichare all hereby incorporated herein by reference in their entireties. Thedisplay is viewable through the reflective element when the display isactivated to display information. The display element may be any type ofdisplay element, such as a vacuum fluorescent (VF) display element, alight emitting diode (LED) display element, such as an organic lightemitting diode (OLED) or an inorganic light emitting diode, anelectroluminescent (EL) display element, a liquid crystal display (LCD)element, a video screen display element or backlit thin film transistor(TFT) display element or the like, and may be operable to displayvarious information (as discrete characters, icons or the like, or in amulti-pixel manner) to the driver of the vehicle, such as passenger sideinflatable restraint (PSIR) information, tire pressure status, and/orthe like. The mirror assembly and/or display may utilize aspectsdescribed in U.S. Pat. Nos. 7,184,190; 7,255,451; 7,446,924 and/or7,338,177, which are all hereby incorporated herein by reference intheir entireties. The thicknesses and materials of the coatings on thesubstrates of the reflective element may be selected to provide adesired color or tint to the mirror reflective element, such as a bluecolored reflector, such as is known in the art and such as described inU.S. Pat. Nos. 5,910,854; 6,420,036 and/or 7,274,501, which are herebyincorporated herein by reference in their entireties.

Optionally, the display or displays and any associated user inputs maybe associated with various accessories or systems, such as, for example,a tire pressure monitoring system or a passenger air bag status or agarage door opening system or a telematics system or any other accessoryor system of the mirror assembly or of the vehicle or of an accessorymodule or console of the vehicle, such as an accessory module or consoleof the types described in U.S. Pat. Nos. 7,289,037; 6,877,888;6,824,281; 6,690,268; 6,672,744; 6,386,742 and 6,124,886, and/or U.S.patent application Ser. No. 10/538,724, filed Jun. 13, 2005 andpublished Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, whichare hereby incorporated herein by reference in their entireties.

Changes and modifications to the specifically described embodiments maybe carried out without departing from the principles of the presentinvention, which is intended to be limited only by the scope of theappended claims as interpreted according to the principles of patentlaw.

1. A vision system for a vehicle, said vision system comprising: acamera disposed at a vehicle and having a field of view exterior of thevehicle; wherein said camera comprises a lens and an imaging arraycomprising an array of photosensing elements having multiple columns ofphotosensing elements and multiple rows of photosensing elements; saidmultiple columns of photosensing elements being generally verticallyorientated relative to ground when said camera is disposed at thevehicle; said multiple rows of photosensing elements being generallyhorizontally orientated relative to ground when said camera is disposedat the vehicle; said multiple rows of photosensing elements comprisingtop rows, middle rows and bottom rows; wherein, with said cameradisposed at the vehicle, top rows are higher above ground than middleand bottom rows; wherein, with said camera disposed at the vehicle,middle rows are higher above ground than bottom rows and are lower aboveground than top rows; wherein, with said camera disposed at the vehicle,middle rows are between top rows and bottom rows; a processor operableto process image data captured by said camera; wherein, when the vehicleis moving, top row brightness values at top rows are determined byprocessing of captured image data by said processor; wherein, when thevehicle is moving, middle row brightness values at middle rows aredetermined by processing of captured image data by said processor;wherein, when the vehicle is moving, bottom row brightness values atbottom rows are determined by processing of captured image data by saidprocessor; wherein contrast of middle row brightness values compared tobottom row brightness values or top row brightness values is determined;and wherein, based on determined contrast of middle row brightnessvalues compared to bottom row brightness values or top row brightnessvalues, an at least partial blockage of said camera is detected.
 2. Thevision system of claim 1, wherein said processor is incorporated incircuitry of said camera.
 3. The vision system of claim 1, wherein saidprocessor is incorporated in circuitry of a control of the vehicle. 4.The vision system of claim 1, wherein said processor is operable to reada selected set of imager register values and compare a contrast of autoexposure control zones, and wherein, responsive to a determination thata range of contrast levels is less than a threshold level, saidprocessor determines that there are contaminants at said lens of saidcamera.
 5. The vision system of claim 4, wherein said processor isoperable to compare a contrast of auto exposure control zones when anauto exposure function of said camera is enabled.
 6. The vision systemof claim 4, wherein said processor compares contrast levels between agenerally middle zone and an upper or lower zone.
 7. The vision systemof claim 4, wherein said processor is incorporated in circuitry of saidcamera.
 8. The vision system of claim 1, wherein the vehicle movingcomprises the vehicle being driven forward on a road.
 9. The visionsystem of claim 8, wherein determining contrast of middle row brightnessvalues compared to bottom row brightness values or top row brightnessvalues comprises determining the difference of middle row brightnessvalues to bottom row brightness values or top row brightness values inthe same column compared to in a different column.
 10. The vision systemof claim 8, wherein said processor is incorporated in circuitry of acontrol of the vehicle.
 11. The vision system of claim 1, wherein, whenan at least partial blockage of said camera is detected, said system atleast one of (i) generates an alert, (ii) adapts processing of capturedimage data to at least partially accommodate for the at least partialblockage and (iii) cleans said lens.
 12. The vision system of claim 1,wherein said camera comprises a CMOS camera.
 13. The vision system ofclaim 12, wherein said imaging array comprises at least 640 columns ofphotosensing elements and at least 480 rows of photosensing elements.14. The vision system of claim 13, wherein said camera is part of amulti-camera birds-eye surround view system of the equipped vehicle. 15.A vision system for a vehicle, said vision system comprising: a cameradisposed at a vehicle and having a field of view exterior of thevehicle; wherein said camera comprises a lens and an imaging arraycomprising an array of photosensing elements having at least 640 columnsof photosensing elements and at least 480 rows of photosensing elements;said at least 640 columns of photosensing elements being generallyvertically orientated relative to ground when said camera is disposed atthe vehicle; said at least 480 rows of photosensing elements beinggenerally horizontally orientated relative to ground when said camera isdisposed at the vehicle; said at least 480 rows of photosensing elementscomprising top rows, middle rows and bottom rows; wherein, with saidcamera disposed at the vehicle, top rows are higher above ground thanmiddle and bottom rows; wherein, with said camera disposed at thevehicle, middle rows are higher above ground than bottom rows and arelower above ground than top rows; wherein, with said camera disposed atthe vehicle, middle rows are between top rows and bottom rows; aprocessor operable to process image data captured by said camera;wherein, when the vehicle is moving, top row brightness values at toprows are determined by processing of captured image data by saidprocessor; wherein, when the vehicle is moving, middle row brightnessvalues at middle rows are determined by processing of captured imagedata by said processor; wherein, when the vehicle is moving, bottom rowbrightness values at bottom rows are determined by processing ofcaptured image data by said processor; wherein contrast of middle rowbrightness values compared to bottom row brightness values or top rowbrightness values is determined; wherein, based on determined contrastof middle row brightness values compared to bottom row brightness valuesor top row brightness values, an at least partial blockage of saidcamera is detected; and wherein, when an at least partial blockage ofsaid camera is detected, said system at least one of (i) generates analert, (ii) adapts processing of captured image data to at leastpartially accommodate for the at least partial blockage and (iii) cleanssaid lens.
 16. The vision system of claim 15, wherein said processor isincorporated in circuitry of said camera.
 17. The vision system of claim15, wherein said processor is incorporated in circuitry of a control ofthe vehicle.
 18. A vision system for a vehicle, said vision systemcomprising: a camera disposed at a vehicle and having a field of viewexterior of the vehicle; wherein said camera comprises a lens and animaging array comprising an array of photosensing elements having atleast 640 columns of photosensing elements and at least 480 rows ofphotosensing elements; said at least 640 columns of photosensingelements being generally vertically orientated relative to ground whensaid camera is disposed at the vehicle; said at least 480 rows ofphotosensing elements being generally horizontally orientated relativeto ground when said camera is disposed at the vehicle; said at least 480rows of photosensing elements comprising top rows, middle rows andbottom rows; wherein, with said camera disposed at the vehicle, top rowsare higher above ground than middle and bottom rows; wherein, with saidcamera disposed at the vehicle, middle rows are higher above ground thanbottom rows and are lower above ground than top rows; wherein, with saidcamera disposed at the vehicle, middle rows are between top rows andbottom rows; a processor operable to process image data captured by saidcamera; wherein, when the vehicle is moving, top row brightness valuesat top rows are determined by processing of captured image data by saidprocessor; wherein, when the vehicle is moving, middle row brightnessvalues at middle rows are determined by processing of captured imagedata by said processor; wherein, when the vehicle is moving, bottom rowbrightness values at bottom rows are determined by processing ofcaptured image data by said processor; wherein contrast of middle rowbrightness values compared to bottom row brightness values or top rowbrightness values is determined; wherein, based on determined contrastof middle row brightness values compared to bottom row brightness valuesor top row brightness values, an at least partial blockage of saidcamera is detected; wherein, when an at least partial blockage of saidcamera is detected, said system at least one of (i) generates an alert,(ii) adapts processing of captured image data to at least partiallyaccommodate for the at least partial blockage and (iii) cleans saidlens; wherein said camera comprises a CMOS camera; and wherein saidcamera is part of a multi-camera birds-eye surround view system of theequipped vehicle.
 19. The vision system of claim 18, wherein saidprocessor is incorporated in circuitry of said camera.
 20. The visionsystem of claim 18, wherein said processor is incorporated in circuitryof a control of the vehicle.